All of our kinetic measurements rely upon access to the corresponding equilibrium behavior of the lipid/water systems under investigation. Thus, temperature-composition (T-C) phase diagram construction is an integral part of our time-resolved studies. A separate ongoing project, concerned with establishing the relationship between lipid molecular structure, overall sample composition and mesophase behavior, also requires T-C phase diagram construction. Much of the mesophase identification and structure characterization required for mapping out a phase diagram can be done using an in-house rotation anode. However, our phase diagrams extend up to 100 C and occasionally go as high as 140 C where time-dependent sample decomposition becomes becomes a major problem. To obviate this limitation, all such measurements at and above 50 C are now done using synchrotron radiation where exposure times are down by an order of magnitude compared to the rotating anode. For this purpose, we have specially built a temperature-regulated sample holder accommodating up to 7 samples at a time that is used in conjunction with a multiple-frame image plate detector. Most recently, the temperature-composition phase diagram of monovaccenin (a C18:1c11 monoacylglycerol) in water was constructed using small-and wide-angle x-ray scattering in the range of ca 0 C to 111 C and ca 0% to 60% (w/w) water in the hearting direction. The phase identified in the system include the lamellar crystalline (Lc) phase, the lamellar liquid crystalline (L) phase, the fluid isotropic (Fl) phase, two inverted cubic phases (Q230,la3d; Q224, Pn3m), and the inverted hexagonal (HII) phase. The monovaccenin/water phase diagram is remarkably similar to that of the monoolein (aC18:1c9 monoacylglycerol)/water system. A portion of the current T-C phase diagram for the monovaccenin system shows evidence of non-equilibrium behavior in the region below 60 C and above 20% (w/w) water that will require more detailed investigation.